The invention is related to a fluid filter having a filter element sealed inside a canister, also called a spin-on type fluid filter. These filters are used in automotive or stationary internal combustion engines that require uninterrupted oil lubrication for moving parts, with continually filtered oil supplied through such a fluid filter in a lubrication circuit.
The available conventional designs of typical spin-on or canister sealed fluid filters include a set of components made both of metallic and/or non-metallic materials, that support the main filtration function of the filter element housed inside the can. A typical conventional fluid filter assembly is shown in FIG. 5, depicting the many multiple components and parts that are used. Many of these components and the processes necessary to assemble them are non-value adding, in that they are not directly related to performing the filtering function. These extraneous non-value adding components and processes are in large part eliminated in the embodiments according to the present invention.
Filter element 11, shown in FIG. 5, has the main function of fluid filtration. It is housed in a can 12 and seamed with the threaded plate and retainer assembly 13 to provide for a mounting arrangement usable for being attached to the mounting base of an engine (not shown). The thread plate assembly 13 has inlet holes 14 used to feed the unfiltered or dirty oil to the filter housing, using passages formed around the central thread hole 15. The central thread hole 15 in turn forms an outlet for the clean oil from the spin-on can filter.
When the engine is started, oil flows to the filter housing through the inlet holes 14, at the design pressure and flow delivered by an oil pump (not shown). The filter is mounted on a threaded stud (not shown) of the engine corresponding to the threaded hole 15, with a piped pathway to return the filtered oil from the inner core of the filter element back to the engine's moving and/or stationary parts that need continuous lubrication under varied operating conditions.
An anti-drain back valve 16 with a cup shaped rubber cone 17 covering the inlet holes 14 of the thread plate helps to retain the fluid (for example lubricating oil) in the housing/can 12 when the engine is turned off. This requirement may be important when the filter is mounted with the case dome up and the threaded plate downwards, or when the filter is oriented in any horizontal mounting. The rubber conical flap 17 unseats from the inlet holes 14 under the force of the pressurized supply of fluid when the engine starts, and allows for inflow of fluid in the filter housing.
When the pump or the engine are off, the conical round flap of the anti-drain back valve seats back on circumferential seat 18 on the metal threaded plate 13, to prevent the flow back from the inlet holes and thus retaining the oil/fluid in the filter housing. This arrangement helps preventing the filter from becoming dry, and prevents air from being trapped in the oil system. Thus, as the engine is started, the oil flow occurs immediately without any air pockets forming in the lubrication circuit.
In conventional filter designs in current production, a filter media element 11 may include a bottom spring support or element guide 19 for filter element 11, to provide sealing between the inlet and the outlet, and for cushioning the design stack-up tolerances of the multiple assembly components involved, by using a compression spring or element guide type supports. The end sealing cap (made of plastic or metal) 20 is used to seal the filter media 11. End cap 20 provides a seat for a relief and bypass valve, which is assembled from a set of components such as a spiral or compression spring 21, a piston 22 and U-clamp or housing 23 that is welded or riveted to the end cap, to hold those components together.
Conventional end cap assemblies include several other components. The exemplary relief valves may be disposed on the thread side top end caps, on the inlet side of the filter, or on the bottom side caps of the filter elements. Such a relief valve is embodied in the filter element to provide the lubrication oil in the event of cold starting conditions, when the engine is turned on after a sufficient lapse of time, or when the filtration media becomes clogged with extensive usage or excessive dirt in the oil. A purpose of the relief valve or bypass valve is to open-up and connect the inlet to the outlet, so the fluid can pass without being filtered. This is done to prevent lubrication starvation when a restriction across the filter is increases to the point where if the relief valve or bypass valve does not open, little or no lubricant would reach the engine.
Some of the principal components used to assemble a filter and to achieve the filtration function are as follow, as shown in FIG. 5.
The external components include:
Filter housing 12.
Thread plate with retainer for assembly with case/can 13.
Seal gasket 10.
The internal components include:
Filter media element 11 with supporting center tube 09.
Anti-drain back valve (ADB) 16.
Relief valve (RV) 08.
Bottom support 19.
Additional supplementary elements and components that make-up the internal parts and assemblies of the filter are listed below. These parts are for the most part made superfluous according to the present invention, which is a one-piece combination anti-drain back and relief valve. The components and parts, as well as the processes that may be avoided according to the present invention include, for example:                Bottom spring/element guide 19,        Relief valve housing 23,        Relief valve spring 21,        Relief valve piston 22,        End cap bottom/top 20,        Welding or riveting process for relief valve assembly 31.        Adhesive bonding of metal or plastic cap to filter element and thermal curing process thereof 32.        
According to embodiments of the invention, the additional components described above are replace by single-piece, resilient end elements of the filter, which combine the functions of the relief valve, of the anti-drain back valve and of various seals. Various manufacturing processes used conventionally to assemble the additional filter components are also avoided, further simplifying the construction.
As will be described in greater detail below, the specially shaped combination components formed from resilient materials, can be assembled using interference fit to retain the parts together, and to retain them in end caps of the filter can 12. For example, an exemplary end cap according to the invention may include an element that defines an end seal and a bottom support for the filter media. Another end cap may include the exemplary combination dual valve element that defines the anti-drain back valve, the relief valve, and an end seal. In addition, the second end cap may be adapted for attachment to an engine face.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.